<dependencies>
    <!-- Spring Boot Security 依賴，用于管理我們的登錄和認證 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-security</artifactId>
    </dependency>
    
    <!-- Spring Boot Data JPA 依賴，用來進行數據庫操作 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    
    <!-- Spring Boot Web 依賴，用來處理 Web 請求 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    
    <!-- MySQL Connector 依賴，畢竟數據還是要放進數據庫的 -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
    </dependency>

    <!-- Lombok 用來減少代碼量，讓我們不用再寫那些煩人的 getter/setter -->
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <optional>true</optional>
    </dependency>
</dependencies>

@Entity
@Table(name = "users")
@Data
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String username;      // 用戶名
    private String password;      // 密碼（重要的東西，當然要加密保存）
    private String email;         // 郵箱
    private String phoneNumber;   // 手機號
}

public interface UserRepository extends JpaRepository<User, Long> {

    Optional<User> findByUsername(String username);

    Optional<User> findByEmail(String email);

    Optional<User> findByPhoneNumber(String phoneNumber);
}

@Service
public class CustomUserDetailsService implements UserDetailsService {

    @Autowired
    private UserRepository userRepository;

    @Override
    public UserDetails loadUserByUsername(String loginInput) throws UsernameNotFoundException {
        Optional<User> userOpt;

        // 判斷輸入的登錄信息類型，來確定是郵箱、手機號還是用戶名
        if (loginInput.contains("@")) {
            // 郵箱登錄
            userOpt = userRepository.findByEmail(loginInput);
        } else if (loginInput.matches("\\d+")) {
            // 手機號登錄
            userOpt = userRepository.findByPhoneNumber(loginInput);
        } else {
            // 用戶名登錄
            userOpt = userRepository.findByUsername(loginInput);
        }

        // 如果用戶不存在，拋出異常
        User user = userOpt.orElseThrow(() -> new UsernameNotFoundException("用戶不存在"));

        // 返回 Spring Security 所需的 UserDetails 對象
        return new org.springframework.security.core.userdetails.User(
                user.getUsername(), 
                user.getPassword(), 
                new ArrayList<>()
        );
    }
}

@Bean
public PasswordEncoder passwordEncoder() {
    return new BCryptPasswordEncoder();
}

@Service
public class UserService {

    @Autowired
    private UserRepository userRepository;

    @Autowired
    private PasswordEncoder passwordEncoder;

    public void registerUser(User user) {
        // 密碼加密
        user.setPassword(passwordEncoder.encode(user.getPassword()));
        userRepository.save(user);
    }
}

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Autowired
    private CustomUserDetailsService userDetailsService;

    @Autowired
    private PasswordEncoder passwordEncoder;

    @Override
    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
        // 配置認證方式，使用我們自定義的 UserDetailsService 和密碼加密方式
        auth.userDetailsService(userDetailsService).passwordEncoder(passwordEncoder);
    }

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        // 設置允許哪些 URL 可以被匿名訪問
        http
            .csrf().disable()
            .authorizeRequests()
            .antMatchers("/login", "/register").permitAll()  // 允許登錄和注冊頁面被訪問
            .anyRequest().authenticated()  // 其他頁面都需要認證
            .and()
            .formLogin()
            .loginPage("/login")  // 設置自定義的登錄頁面
            .defaultSuccessUrl("/home", true)  // 登錄成功后跳轉的頁面
            .permitAll()
            .and()
            .logout()
            .permitAll();


    }
}